1. Field
The present invention relates generally to wireless communications, and more specifically to a tapered multiband antenna.
2. Background
Wireless communication systems are widely deployed to provide various types of communication such as voice and data. A typical wireless data system, or network, provides multiple users access to one or more shared resources. A system may use a variety of multiple access techniques such as Frequency Division Multiplexing (FDM), Time Division Multiplexing (TDM), Code Division Multiplexing (CDM), and others.
Example wireless networks include cellular-based data systems. The following are several such examples: (1) the “TIA/EIA-95-B Mobile Station-Base Station Compatibility Standard for Dual-Mode Wideband Spread Spectrum Cellular System” (the IS-95 standard), (2) the standard offered by a consortium named “3rd Generation Partnership Project” (3GPP) and embodied in a set of documents including Document Nos. 3G TS 25.211, 3G TS 25.212, 3G TS 25.213, and 3G TS 25.214 (the W-CDMA standard), (3) the standard offered by a consortium named “3rd Generation Partnership Project 2” (3GPP2) and embodied in “TR-45.5 Physical Layer Standard for cdma2000 Spread Spectrum Systems” (the IS-2000 standard), and (4) the high data rate (HDR) system that conforms to the TIA/EIA/IS-856 standard (the IS-856 standard). Example non-cellular wireless networks include the various IEEE 802.11 standards.
Wireless Wide Area Networks (WANs) are deployed throughout the world using various frequencies and communication technologies. Laptop manufacturers, as well as other user terminal manufacturers, would benefit from a low-cost universal antenna integrated within the laptop or user terminal that can function on the many different wireless WANs deployed anywhere in the world. There are several WAN frequency bands that range from 824 MHz to 2500 MHz. The advantage of a low-cost integrated universal antenna is that it may be installed in a laptop and shipped anywhere in the world, reducing mass production volume costs and avoiding the need for differentiated product lines for units going to different locations. Consumers may also appreciate an integrated antenna as they could avoid purchasing a separate device, such as a PCMCIA card or other device to use as a wireless WAN modem. Such a customer may also avoid worrying about lost or misplaced devices. A universal antenna would allow the customer to travel anywhere in the world and access wireless Wide Area Networks in those locations.
In current implementations, integrated antennas for user terminals, such as laptop computers, are not adaptable for use within the multiple frequency ranges deployed throughout the world. Universal access modems currently available require an external PCMCIA card, with an external antenna attached. The antenna extends approximately one inch from the outside case of the laptop. Although the antenna allows for access over a wide range of frequency bands, there are several problems. The customer has to purchase the PCMCIA card separately. The PCMCIA card could get lost or misplaced. And, since the antenna extends outside the laptop case, it is prone to damage. Currently available multi-frequency band antennas are too large to fit within a mobile user terminal of small size, such as a notebook computer. There is therefore a need in the art for a small size multi-band antenna that lends itself well to integration within a relatively confined space.